<!DOCTYPE html>
<html lang="zh-CN">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        const num=[10,20,30]
      const result=num.reduce((v,s)=>v+s,0)
      console.log(result);

        const list=['a','b','c']
        const res=list.reduce(,'')

    </script>
</body>
</html>